It's an ingenious idea, using interlocking floor mat pieces as a blocking surface for your knitted items. They can handle being stuck with pins, they can keep moisture from passing to the surface beneath, and best of all, they can be moved around like puzzle pieces to create the size you need for the piece you're blocking.

Using interlocking floor mat pieces—the kind usually reserved for children's play rooms—is not a new idea. But Julie Weisenberger has taken the concept one step further and created a blocking kit using interlocking mat pieces that have been customized expressly for the purpose of blocking.

The Kit
For $48 plus shipping, you get nine blocking tiles, a cotton blocking cloth, a set of 20 blocking pins, and an instruction pamphlet, all packed in a snazzy orange carrying bag.

The blocking tiles are made of a dense, lightweight white foam that has a thin waterproof backing. The tile surface is covered with a low, lightly barbed off-white fabric pile that helps hold knitted fabric in place and provides a vapor barrier for faster drying.

The blocking cloth comes from Egypt and is made of 100% Egyptian cotton.

Why Block?To give your knitted projects a crisp, professional finish, you really want to block them. But the extent to which you block, and when you block, is as highly personal as the extent to which you swatched (or didn't!) before beginning the project. Which basically means that no two knitters will block exactly the same way.

Some knitters prefer scientific precision, using rigid foam blocking boards that are pre-printed with gridlines and measurements so that you can be sure your sleeve is exactly 9.1 inches at the cuff, and not one sixteenth of an inch over. The tiles in the Knitter's Block kit have no measurement markings or gridlines whatsoever.

Some knitters share their homes with curious children and four-legged friends who enjoy marching across any and all surfaces, even those covered with pieces of knitting held down with sharp pins. Those homes may be best served by firm foam blocking boards that you can prop or hang against a wall—the tiles in the Knitter's Block kit can't really be propped against a wall. Actually, you could line the tile backs with Velcro and line your wall with companion velcro stripping if you really wanted, but you'd need a dedicated wall of Velcro to accommodate all the different possible tile configurations.

But for knitters who've been using their bed or carpet to block their garments, and for those who groan at the thought of storing giant pieces of fabric-covered foam insulation for the few projects they manage to finish and block every year, this kit is absolutely ideal. It is compact, flexible, and extremely portable.

Every Rose Has Its Thorns
Alas, it does have some shortcomings. The most notable one is the fact that the kit only contains nine blocks. In square configuration, that's only about 36 inches square. For adult-sized sweaters, you'll need to batch-process your blocking because two sleeves, a front, and a back will not fit on that surface.

Likewise, if you tend to knit any kind of significant lace—which can grow massively with blocking—you won't have enough square footage. To give you a sense of scale, I set out a small shoulder shawl (from The Knitter's Stash)...

...and the Endpapers Shawl from my book. Just laying them out as-is without re-blocking them at all, the shoulder shawl just fit. The Endpapers Shawl wanted at least three, maybe four more blocks.

For this reason, I would love to see a "Big Block" kit-expansion option where you can purchase more blocks without needing to invest in a whole new kit.

Not Quite Pinned Down
The blocking pins that come with the kit are a great start. But for any significant blocking you'll want to invest in at least three times more pins. You can never have too many blocking pins. To highlight every single scallop in the edging of the orange shawl, for example, I would have needed 60 pins—and this kit only comes with 20.

While you're picking up more blocking pins, invest in a good set of stainless steel blocking wires (such as Fiber Fantasy's Blockers Kit, which retails for $24). For thin fabric and any kind of lace where you want consistent straight edges, these are essential. You run the wires along the edge stitches and then use the needles to secure the wires. Need to block more? Just pull each wire out by another half inch.

Where There's Water
Blocking involves moisture. The back of the tiles is coated with a waterproof surface, but I found a few small gaps in the interlocking corners where moisture could still seep through. We don't tend to block pieces that are sopping wet, so this isn't a critical issue. But if you're at all concerned, you may not want to set this out on your great grandmother's mahogany dining table—especially since any stray blocking-pin tip pushed too hard could also do damage.

Where there's moisture, there's the potential for color bleeding. Yarn can bleed when you're blocking it. Ideally you will have knit swatches in the yarn before you even began the project, and you will have washed those swatches to discover any possible bleeding, shrinking, stretching, or other wash-related changes. Because it would be very depressing to have your beautiful off-white blocking boards turned forever another color.

Weisenberger's modifications do make for a better blocking mat. The pile surface definitely does help grip the fabric and provides a vapor barrier for faster drying. At $48 plus shipping, Knitter's Block is priced competitively with the other knitwear blocking products on the market. An 18 x 24-inch blocking board averages $45, and a 33 x 51-inch board runs you $76 (both of which can be found at Angelika's). They're all pretty pricey but they do tend to last longer than simple cloth-covered foam insulation boards. The benefit of this kit is its flexibility, letting you rearrange the squares to make different shapes depending on what you're blocking—up to a point.

If you're on a budget, if your carpet and bed are begging for relief from those blocking pins, or if you're constantly overrunning the borders of your existing blocking boards, here's another option. Consider getting a children's foam interlocking play mat instead. Wondermat's Standard Series 5/8-inch thick mats start at $1.75 per square foot (plus shipping). They're also made of a dense EVA foam with waterproof lining, they're washable, and they come in all sorts of bright colors.

A few things to note about these mats: They don't have the pile fabric surface, they don't come with blocking needles or instructions or a convenient carrying bag, and I do not know how much heat they can withstand compared to the Knitter's Block boards. But they are a compromise—especially if you tend to block large pieces of lace that won't fit on a Knitter's Block kit, and you're not hooked on using a super-hot iron for blocking.